Introduction
Innate immunity is the body’s first line of defense against pathogens and plays a crucial role in protecting individuals from infections. This form of immunity is not acquired through previous exposure or immunization but is present from birth. While innate immunity is primarily attributed to the body’s physical barriers and cellular responses, it is also influenced by genetic factors, body temperature, inflammation, fever.
Genetic Factors
- Natural immunity is also due to genetic factors; thereby immunity differs at the level of species, racial and individuals.
Species Immunity
- Species immunity refers to the resistance exhibited by all members of a particular species against a specific pathogen.
- It is fascinating to observe how different species display varying susceptibilities to different diseases.
- For example, rats are insusceptible to diphtheria, while guinea pigs and human beings are highly susceptible to the same pathogen.
- Likewise, human beings are highly susceptible to the common cold, whereas dogs are not affected by the virus causing the cold.
- Another example is measles, which exclusively targets human beings and cannot infect non-primates.
Racial Immunity
- Within a species, different races may exhibit differences in susceptibility to infections, which is known as racial immunity.
- For instance, in the United States, Negroes are more susceptible to tuberculosis than whites.
- These variations in susceptibility can be attributed to genetic factors that differ among racial populations.
Individual Immunity
- Individual immunity refers to the differences in innate immunity observed among individuals of the same race.
- Studies involving human twins have shed light on this phenomenon.
- Identical twins, who share the same genetic makeup, exhibit similar degrees of resistance or susceptibility to diseases such as leprosy and tuberculosis.
- On the other hand, heterozygous twins, who have different genetic compositions, do not show such correlations in immunity.
Body Temperature
- The body’s temperature also plays a significant role in determining innate immunity.
- Pathogens, such as tubercle bacilli, which are pathogenic to warm-blooded mammals, cannot infect cold-blooded animals.
- For instance, hens, with a body temperature of about 40°C, are naturally immune to anthrax.
- However, if their body temperature is lowered, they become susceptible to infection.
- Additionally, certain bacteria, like gonococci, are readily killed at temperatures above 40°C. In the past, fever therapy was used to combat gonococcal infections before the discovery of antibiotics like penicillin.
Inflammation
- Injury to tissues and the entry of pathogens trigger a series of cellular and vascular changes known as inflammation.
- This immune response is characterized by four important features: heat, pain, redness, and swelling.
- At the site of inflammation, several significant changes occur.
- Firstly, the arterioles constrict initially and then dilate, thereby increasing blood flow to the affected area.
- Secondly, the walls of the capillaries become more permeable, leading to fluid exudation and subsequent swelling.
- Lastly, polymorphonuclear leukocytes, also known as microphages, escape from the blood vessels and accumulate at the site of injury through diapedesis.
- This accumulation facilitates the process of phagocytosis, where microorganisms and damaged tissues are engulfed and destroyed.
Fever
- Fever, characterized by a rise in body temperature following an infection, serves as a natural defense mechanism of the body.
- Elevated temperature helps accelerate physiological processes and may also contribute to the destruction of infecting pathogens in certain cases.
- Furthermore, fever stimulates the production of interferon, a substance that aids in recovery from viral infections.
Conclusion
Innate immunity, the body’s first line of defense against pathogens, is influenced by various genetic factors. Species immunity, racial immunity, and individual immunity demonstrate how genetic variations can impact an individual’s susceptibility to infections. Factors such as body temperature, inflammation, and fever also play crucial roles in innate immunity and contribute to the body’s ability to fight off pathogens. Understanding the genetic underpinnings of innate immunity enhances our knowledge of how individuals and populations respond to infectious diseases.
FAQs
Q. Can innate immunity be improved through genetic interventions?
A. While genetic factors play a role in determining innate immunity, it is important to note that genetic interventions for enhancing innate immunity are still in the realm of research. Currently, interventions mainly focus on optimizing overall health and bolstering the body’s natural defense mechanisms.
Q. Are genetic factors the sole determinants of innate immunity?
A. No, genetic factors are not the sole determinants of innate immunity. Other factors, such as environmental conditions, overall health, and lifestyle choices, also influence an individual’s innate immune response.
Q. Can variations in racial immunity be attributed solely to genetics?
A. Racial immunity variations are influenced by a combination of genetic and environmental factors. While genetic differences among racial populations contribute to varying susceptibility to infections, environmental factors, such as exposure to pathogens and socio-economic conditions, also play a role.
Q. How does innate immunity differ from acquired immunity?
A. Innate immunity is present from birth and provides immediate protection against pathogens. Acquired immunity, on the other hand, is developed over time through exposure to pathogens or through immunization. Acquired immunity is more specific and tailored to the pathogens encountered by an individual.
Q. Are there any drawbacks to fever as a defense mechanism?
A. While fever serves as a natural defense mechanism, extremely high temperatures can be detrimental to the body. Prolonged or excessively high fever can cause discomfort, dehydration, and potential damage to body tissues. It is important to monitor and manage fever appropriately.